Testing partially composite neutrinos with neutrino beams

With the advent of new high energy, luminous neutrino sources, it is possible to test whether or not the neutrino is coupled to some strongly interacting sterile sector. We propose to study this property by looking for high-energy neutrino scattering events in which the neutrino “disintegrates” into dark jets. Depending on the lifetime, the experimental signature can be either missing energy or visible displaced events in the detector. We derive new bounds from the old NuTeV data, and assess the sensitivity of upcoming experiments such as SHiP and the Forward Physics Facility at CERN.